As Marvel’s Agents of S.H.I.E.L.D. hits the 100-episode milestone (this Friday at 9/8c), TVLine invited the ABC drama’s cast and creatives to reflect on the biggest bombshells that have been dropped across four-and-a-half seasons.

As you might imagine, a recurring theme among their answers involved Season 1’s direct tie-in with the Marvel Cinematic Universe — the episode “Turn, Turn, Turn,” which aired just days after Captain America: The Winter Soldier revealed that S.H.I.E.L.D. had been infiltrated by sleeper HYDRA agents. As such, the Strategic Homeland… whatever was disbanded on the big screen, forcing the TV series to do same and send its titular agents underground, while also revealing that one of their own was a traitor. Watch that scene below:

“The Ward reveal was probably the turning point for us,” co-showrunner Jed Whedon told TVLine at the Episode 100 party. “It’s when we were finally allowed to have spies, say HYDRA, and we got all that momentum out of that. It sort of defined the show. That was to us the big moment.”

“We were finally free,” added co-showrunner Maurissa Tancharoen. “We didn’t have to keep the word HYDRA under wraps, which was very liberating.”

Of course, “There have been other [big twists] along the road,” Whedon noted. “The thing we love is that the cast always gets so enthusiastic about playing these turns that it makes it rewarding — not only for fans but for us as writers.”

S.H.I.E.L.D. front man Clark Gregg echoed the showrunners. “I still have to say, the one where the reveal of HYDRA dovetailed with Winter Soldier was pretty spectacular,” he offered. But also, “Having Skye become Daisy become Quake was pretty great,” Gregg said. “I also like a lot of the stuff in the Framework, that shift of reality. I personally really loved getting to play this apparently paranoid history teacher whose deranged visions turned out to be reality.”

Skye’s aforementioned transformation into something… other, midway through Season 2, marked a seismic shift for then-cast member Brett Dalton. When S.H.I.E.L.D. first premiered, he recalled, “We were a show about the guys who didn’t have powers and had to clean up after Thor and Hulk and everybody destroyed New York. We were the ones who had to investigate ‘the 0-8-4’ when that wasn’t necessarily on anybody else’s radar. So we were always badgering the writers, ‘Come on, one of us has something, right? What’s the thing?’ And they played it out for so long that we were like, ‘Oh man, I guess nobody here has powers.’ So the big reveal of Skye being an Inhuman, and being Quake, and part of the Marvel Universe already, was pretty amazing.”

“The most shocking when Ward was revealed as being HYDRA,” said Elizabeth Henstridge, who plays Simmons. “Emotionally, that tore us apart a little bit [as a cast]. I don’t know that it was a favorite moment, because it was so disrupting, but that’s certainly the one that sticks out.” Ward’s “Manchurian Candidate” betrayal also topped Iain de Caestecker’s list, though a more recent development was also at the tip of his tongue: “Fitz and Simmons getting engaged is a bit of a shock.”

Though Henry Simmons didn’t sign up with S.H.I.E.L.D. until Season 2, the Ward reveal that predated his arrival still made an impression on him. But to that, he added, “I was shocked when B.J. [Britt]’s character [Agent “Trip” Triplett] died,” nicked by a terrigen crystal shard and then pulverized during Skye’s explosive transformation.

A betrayal other than Ward’s is what most shook relative newcomer Natalia Cordova-Buckley, who didn’t start regularly recurring until late Season 3. “The LMD May stuff was really shocking to me because it was in my first [full] season on S.H.I.E.L.D. and it was the first time that I was seeing one of my friends, in fiction and in reality, kind of betraying us,” she shared. “I was like, ‘No! I don’t want her to be bad!'”

But wait, there’s more… twists to be had, with the current season barely half over!

“There’s a big one coming up, I don’t know if I can talk about it…,” teased Simmons. Added Henstridge, “There are some pretty shocking twists in this season, still to come, that are my favorite — because they’re kind of nice ones.” Gregg similarly expects this season’s very final stretch to drop some jaws. “I suspect there are some more coming this season,” he said, “although in all honesty, I won’t get to know what they are until they let me read the last five scripts!” (With reporting by Scott Huver)